KCS and RDR 10 Hz Operation Chris Adolphsen BAW2, SLAC 1/20/2011

Assumptions At lower gradients, reduce modulator voltage and increase pulse rate so nominal average modulator input power not exceeded - thus the charging power supplies would see the same or smaller load (which is roughly constant), and the AC power capacity would not have to be increased. Time Modulator Cell Voltage Same Slope Discharge Level Differs Every Other Pulse Additional line ripple introduced by alternating discharge levels would need to be reduced in the site electrical distribution system. 5 Hz10 Hz

SLAC/KEK Toshiba 10 MW MBK Efficiency and Output Power Versus Beam Voltage

Cases Considered 250 GeV, 5 Hz –Modulator Voltage = 117 kV, Klystron Power = 10 MW, Kly Eff = 68% 150 GeV, 5 Hz –Cavity QL = (150/250) times that at 250 GeV – fill time shortened by the same factor –Modulator Voltage = 99.5 kV, Klystron Power = 6 MW, Kly Eff = 60% 125 GeV, 5 Hz –Assume same QL as for 150 GeV (cannot switch between pulses) –Required rf power = 6 MW * ¼ * ( /150)^2 = 5.04 MW, just slightly more as if QL were optimized for 125 GeV –Reflected power during beam = 6 MW * ¼ * ( /150)^2 =.04 MW –Also the fill time is (150/125)*log( /150)/log(2) = 1.05 times longer than if QL were optimized for 125 GeV –Modulator Voltage = same as 150 GeV case (although may be able to run at a lower modulator voltage every other pulse). To lower the RF power for KCS, reduce number of ‘on’ klystrons by 1 – (5.04/6)^0.5 = 8%, while for the RDR case, reduce the rf drive power.

Results 10 Hz

Summary The half current case clearly exceeds the RDR average modulator input power limit when running at 150 GeV (5 Hz) GeV (5 Hz), but this added capacity is needed anyway run at 250 GeV (5 Hz) with half current. The full current case is marginal at 10 Hz although if can alternate the modulator voltages, only 4% more AC power would be required. The half bunches, same rf pulse case for 150 GeV (5 Hz) GeV (5 Hz) would work and does not require any increased capacity (AC, cooling or cryo)

Klystron Cluster Scheme Tests Resonantly power a 0.5 m diameter, pressurized (1 atm N2), 10 m long aluminum pipe to 300 MW TE01 mode field equivalent in 1 ms pulses

Time of Position 2 markers (T1,T2) are ~ 1 ms later than those from Position 1, which suggest events are much closer to Position 1 (5 m / 5100 m/s ~ 1 ms) T1 T2 Acoustic Sensor Breakdown Localization CTO KW input power yields 300 MW equivalent surface fields in the pipe - see bkd every ~ 15 hours, maybe from CTO or upstream – rate seems very pressure dependent ‘Big Pipe’ Operation

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